Here's the deal. I have 2 3 days-passes and me and my friend can't come on Thursday.
We need 2x2 tickets for Friday and Saturday only.
Or even a 1 day ticket for Saturday.

So

If someone has 2x2 tickets or 2x1 ticket and wantes a 3 DAYS PASSES here's your chance to have them.
We would proceed to an exchange o names basically.
I sell you my 2 3days passes and you sell me your 2x 1 or 2 tickets
We could arrange something with the organizer switching names or something.
Well if you have a functioning brain you get the idea